eslint-plugin-metafizzy/src/computed-property-spacing.js

ESLint config for Metafizzy

function create( context ) {

  let sourceCode = context.getSourceCode();

  function reportProperty( node, property ) {
    if ( !node.computed ) {
      return;
    }

    let openBracket = sourceCode.getTokenBefore( property );
    let closeBracket = sourceCode.getTokenAfter( property );
    let hasOpeningSpace = sourceCode.isSpaceBetweenTokens( openBracket, property );
    let hasClosingSpace = sourceCode.isSpaceBetweenTokens( property, closeBracket );

    let isSingleCharIdentifier = property.type === 'Identifier' &&
      property.name.length === 1;

    if ( property.type === 'Literal' || isSingleCharIdentifier ) {
      // Strings, Numbers, and single-character Identifiers like `i` reject spaces
      if ( hasOpeningSpace ) {
        context.report({
          node: node,
          loc: openBracket.loc,
          messageId: 'unexpectedOpeningSpace',
          fix: function( fixer ) {
            return fixer.removeRange([ openBracket.range[1], property.range[0] ]);
          },
        });
      }
      if ( hasClosingSpace ) {
        context.report({
          node: node,
          loc: closeBracket.loc,
          messageId: 'unexpectedClosingSpace',
          fix: function( fixer ) {
            return fixer.removeRange([ property.range[1], closeBracket.range[0] ]);
          },
        });
      }
    } else {
      // everything else require spaces
      if ( !hasOpeningSpace ) {
        context.report({
          node: node,
          loc: openBracket.loc,
          messageId: 'missingOpeningSpace',
          fix: function( fixer ) {
            return fixer.insertTextAfter( openBracket, ' ' );
          },
        });
      }
      if ( !hasClosingSpace ) {
        context.report({
          node: node,
          loc: closeBracket.loc,
          messageId: 'missingClosingSpace',
          fix: function( fixer ) {
            return fixer.insertTextBefore( closeBracket, ' ' );
          },
        });
      }
    }
  }

  return {
    Property: function( node ) {
      reportProperty( node, node.key );
    },
    MemberExpression: function( node ) {
      reportProperty( node, node.property );
    },
  };
}

module.exports = {
  meta: {
    type: 'layout',
    fixable: 'whitespace',
    docs: {
      description: 'enforce spacing inside computed property brackets',
      category: 'Stylistic Issues',
    },

    messages: {
      missingOpeningSpace: 'Space missing after opening bracket `[`',
      missingClosingSpace: 'Space missing before closing bracket `]`',
      unexpectedOpeningSpace: 'Singular value in brackets. Unexpected space after `[`',
      unexpectedClosingSpace: 'Singular value in brackets. Unexpected space before `]`',
    },
  },

  create: create,
};